Method of manufacturing armature coil

ABSTRACT

A method of manufacturing an armature coil includes steps of arranging a plurality of coil conductors of the armature coil between an end metal die and a back portion metal die on a lower metal die; pressing, with the upper metal die in a pressing direction, the plurality of the coil conductors arranged between the end metal die and the back portion metal die on the lower metal die; and removing coil conductors that become formed in a convex shape and a concave shape from the lower metal die. The upper metal die may be provided with an inclined portion on a lower metal die side of the upper metal die, and the upper metal die may be configured to be pressed such that a space is formed by the dies, the space having a width that gets gradually narrower.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a divisional of U.S. application Ser. No. 15/639,090filed Jun. 30, 2017, which application is a divisional of U.S.application Ser. No. 14/650,335 filed Jun. 8, 2015, which is a 371National Stage Application of PCT/JP2013/062342 filed Apr. 26, 2013; theabove-noted applications are incorporated herein by reference in theirentirety.

TECHNICAL FIELD

The present invention relates to an armature coil for use in a rotaryelectric machine and a method of manufacturing the same and, moreparticularly, relates to the shape of the armature coil.

BACKGROUND ART

Hitherto, a coil wound around a stator or a rotor of a rotary electricmachine passes through in line in slots that are holding portions forthe coil. More particularly, there are disclosed a coil whose coilconductor cross-section is formed in a rectangular shape or atrapezoidal shape along the shape of the slot and a coil whose coilconductor shape is formed in a trapezoidal shape that is differentdepending on a slot insertion position. Furthermore, one side and theother side of the coil conductor are formed in parallel planes. (Referto FIG. 12 of Patent Document 1.)

Moreover, in a conventional method of manufacturing a coil, there isdisclosed one in which at least a portion of a coil to be inserted intoa slot is inserted and arranged in a forming die having a previouslydetermined trapezoidal shaped groove and a coil conductor is pressed bya pressing die to be formed in a trapezoidal shape. Furthermore, oneside and the other side of the coil conductor are formed in parallelplanes. (Refer to Patent Document 2.)

RELATED ART DOCUMENT Patent Document

Patent Document 1: Japanese Patent Gazette No. 3474660 Patent Document2: Japanese Examined Patent Publication No. H7-32551

SUMMARY OF THE INVENTION Problems to be Solved by the Invention

Even if the above-described conventional armature coil and method ofmanufacturing the same, a space factor is improved by deforming to thecoil conductor shape along the slot shape. However, further high outputof the rotary electric machine is required in recent years; and aproblem exists in that the space factor needs to be further improved.

The present invention has been made to solve the above describedproblem, and an object of the present invention is to provide anarmature coil and a method of manufacturing the same, which can furtherimprove a space factor.

Means for Solving the Problems

According to the present invention, there is provided an armature coilin which a plurality of slots through which coil conductors pass areannularly arranged and a plurality of the coil conductors pass throughthe inside of the slot in line. In the armature coil, thecircumferential width of the plurality of the coil conductors is formedin a substantially trapezoidal shape which gets narrower toward theradially inner side and the cross-sectional areas of the plurality ofthe coil conductors in the slot are each substantially the same and thecircumferential width thereof is formed narrower as the coil conductoris arranged toward the radially inner side; and one coil conductor isformed in a convex shape and another coil conductor is formed in aconcave shape along the convex shape.

Furthermore, according to the present invention, there is provided amethod of manufacturing an armature coil including the steps of:arranging a plurality of coil conductors on a lower metal die having ataper-shaped groove substantially the same as a slot which is wound withthe plurality of the coil conductors of the armature coil and is formedin a trapezoidal shape which gets narrower in width toward the radiallyinner side; pressing the coil conductors arranged in the groove of thelower metal die by an upper metal die having a rod-shaped end portionslightly narrower than the width of the groove; forming more flattenedtoward the coil conductor arranged at the end of the groove by beingpressed to a predetermined position by the rod-shaped end portion of theupper metal die, forming an aspect ratio smaller toward the coilconductor near an opening portion of the groove, and forming such thatone coil conductor is formed in a convex shape and another coilconductor is formed in a concave shape along the convex shape at betweenthe coil conductors; and removing the coil conductors formed in theconvex shape and the concave shape from the lower metal die.

Further, according to the present invention, there is provided a methodof manufacturing an armature coil, including the steps of: having alower metal die which is provided with an end metal die at a left endportion and a back portion metal die at a right end portion and an uppermetal die which is provided with an inclined portion on the lower metaldie side and is to be pressed, forming such that a space formed by therespective metal dies is substantially the same as the shape of a slotand the width of the space gets gradually narrower toward the directionof the end metal die when the upper metal die is moved to come incontact with the upper surfaces of the end metal die and the backportion metal die of the lower metal die, and arranging a plurality ofcoil conductors of the armature coil between the end metal die and theback portion metal die on the lower metal die; pressing the plurality ofthe coil conductors arranged between the end metal die and the backportion metal die on the lower metal die by the upper metal die; formingmore flattened toward the coil conductor near the end metal die by beingpressed to a position coming in contact with the upper surfaces of theend metal die and the back portion metal die of the lower metal die bythe upper metal die, forming an aspect ratio smaller toward the coilconductor near the back portion metal die, and forming such that onecoil conductor is formed in a convex shape and another coil conductor isformed in a concave shape along the convex shape at between the coilconductors; and removing the coil conductors formed in the convex shapeand the concave shape from the lower metal die.

Advantageous Effect of the Invention

According to the present invention, the degree of joining between thecoil conductors is increased by forming the shape of a coil conductorcross-section in the slot in concave and convex shapes and therebyimproving a space factor, whereby, as a result, there can be providedthe armature coil of a high output rotary electric machine.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a partially sectional view showing a coil insertion state inan armature coil according to Embodiment 1 of the present invention;

FIGS. 2(a), 2(b) are each a coil forming process view by a coil formingapparatus in an armature coil according to Embodiment 2 of the presentinvention; and

FIGS. 3(a), 3(b) are each a coil forming process view by a coil formingapparatus in an armature coil according to Embodiment 3 of the presentinvention.

MODE FOR CARRYING OUT THE INVENTION Embodiment 1

Hereinafter, Embodiment 1 of the present invention will be describedwith reference to FIG. 1. FIG. 1 describes on a case where a rotaryelectric machine serves as a motor and a stator is used as an armature;however, FIG. 1 can also be applied to a case where a rotor is used.FIG. 1 is a partially sectional view showing a coil insertion state inan armature coil according to Embodiment 1 of the present invention.

The stator is formed in a cylindrical shape by a stator core 1 which isconfigured by laminating a plurality of thin steel sheets; and a largenumber of teeth 2 are arranged toward the radially inner side. A slot 3is formed between these teeth 2. A first coil conductor 4 a, a secondcoil conductor 4 b, a third coil conductor 4 c, and a fourth coilconductor 4 d or a first coil conductor 4 e, a second coil conductor 4f, a third coil conductor 4 g, and a fourth coil conductor 4 h passthrough these slots 3 to constitute an armature coil 4.

The following description will be made such that the armature coil 4passing through the slot 3 is composed of, for example, four coilconductors. The armature coil 4 constituting a winding of the stator maybe of a pine needle shaped segment coil or one in which a continuouswire is regularly formed in a wave shape. The armature coil 4 isgenerally classified into a crossover portion (not shown in the drawing)outgoing from a tooth 2 and incoming into another tooth 2 and a straightslot insertion portion to be inserted into the slot 3. Moreparticularly, the slot insertion portion has an important role in whichcurrent flowing in the armature coil 4 makes the rotor (not shown in thedrawing) rotate by repulsion or attraction between magnetic poles of therotor via the teeth 2. More specifically, in the case of designing anefficient motor, as for the armature coil 4, reduction in copper loss iseffective and therefore an improvement of a space factor is an importantfactor. In this case, the space factor is termed as the ratio of thecross-sectional area of the armature coil 4 to the cross-sectional areaof the slot.

A plurality of coil conductors of the armature coil 4 are wound and areinserted into the slot 3 of the stator core 1 which is configured bylaminating the plurality of thin steel sheets; and therefore, thearmature coil 4 is covered by a coating in order to secure insulationfrom the surrounding stator core 1. For such occasions, it is possibleto form the cross-section of each coil conductor of the armature coil 4in a polygonal shape such as a rectangular shape and a trapezoidalshape; however, such a shape has corner portions, the coating of thecorner portions is usually thinner than a straight portion, and apinhole is also likely to be occurred; and accordingly, there is a casewhich does not standup to actual use. Therefore, a quadrilateral shapewhose corners are rounded is often used.

On the other hand, the stator is a cylindrical shape; and an innerdiameter is inevitably shorter than an outer diameter and the peripheryof the inner diameter is also shorter than the periphery of the outerdiameter. There exists the slot 3 whose inner diameter side width issubstantially equal to an outer diameter side width and the innerdiameter width is smaller than the outer diameter width as shown inFIG. 1. In the case where the inner diameter width is equal to the outerdiameter width, the end side width of the tooth 2 must needs be smallerthan a root width thereof. Magnetic flux passing through the tooth 2 isrestricted by the narrowest width of the tooth 2; and, in a sense, it isunnecessary to pass the magnetic flux in the root having a too largewidth. Accordingly, in the case where the width of the tooth 2 isscarcely changed, the width of the slot 3 gets inevitably narrowertoward the inner diameter.

In the case of inserting the first coil conductor 4 a, the second coilconductor 4 b, the third coil conductor 4 c, and the fourth coilconductor 4 d, or the first coil conductor 4 e, the second coilconductor 4 f, the third coil conductor 4 g, and the fourth coilconductor 4 h of the armature coil 4 in such the inner side tapered slot3, it is effective to form the armature coil 4 having a coilcross-section along the inside shape of the slot 3 in order to improvethe space factor. Furthermore, in consideration of appropriately flowingcurrent in the armature coil 4, the same cross-sectional area is moreconvenient. Based on these considerations, it is effective to form thearmature coil 4 in a trapezoidal shape in quadrilateral shapes and toform the aspect ratio larger toward the inner diameter side.

Furthermore, the inserted armature coil 4 is composed of a plurality ofcoil conductors, it is troublesome in view of a process to form eachcoil conductor into a predetermined different shape one by one andforming cost also increases; and therefore, it is more expedient to formthe plurality of coil conductors into a predetermined shape in bundle.Further, it is more advantageous spatially to narrow the intervalbetween the respective coil conductors of the armature coil 4 and tofirmly attach as much as possible. Moreover, there is also an effectthat heat dissipation properties are the same between the respectivecoil conductors of the armature coil 4. Consequently, one coil conductorof the armature coil 4 is formed in a convex shape at one radially endand another coil conductor of the armature coil 4, which firmly attachesto one coil conductor, is formed in a concave shape at the otherradially end along the convex shape; and thus, contact propertiesbetween the respective coil conductors of the armature coil 4 areincreased and therefore the space factor is improved.

Furthermore, the cross-sectional areas of the respective coil conductorsof the armature coil 4 are all the same; and therefore, for example, theaspect ratio of the first coil conductor 4 a of the armature coil 4, thefirst coil conductor 4 a being located on the inner diameter side of theslot 3, is larger than that of the second coil conductor 4 b of thearmature coil 4, the second coil conductor 4 b being located on theouter diameter side. Therefore, it is more advantageous to make theaspect ratio larger, that is, to make the convex portion larger at oneend of the first coil conductor 4 a on the inner diameter side of thearmature coil 4. In FIG. 1, the outer diameter side of the first coilconductor 4 a of the armature coil 4 is formed in the convex shape andthe inner diameter side of the second coil conductor 4 b of the armaturecoil 4 on the outer layer side thereof is formed in the concave shapealong the convex shape. Similarly, although there is a difference in thesize of the convex shape and the concave shape, the third coil conductor4 c and the fourth coil conductor 4 d of the armature coil 4 are alsoformed in the convex shape and the concave shape. Incidentally, thesides coming in contact with the insides of the slot 3 are innerdiameter side tapered lines (lines which get narrower toward the innerdiameter side) along the shape of the slot 3. Further, its straightportion is joined to the convex shaped portion and the concave shapedportion with roundness formed at their corners.

Furthermore, there is shown an example in which the direction of theconvex shape of the coil conductors 4 e to 4 h of the armature coil 4 isan opposite direction as compared to that of the coil conductors 4 a to4 d of the armature coil 4. The convex shape may be placed in the samedirection as the whole stator or may be changed, for example, for eachphase. In this regard, however, it is not expedient to change thedirection of the convex shape in the same slot 3 from a viewpoint of thespace factor. Furthermore, in the case where four or more coilconductors of the armature coil 4 are inserted in the slot 3, and in thecase of a pair of the armature coils 4 or in the case of, for example, apair of each two coil conductors of the armature coil 4 from a viewpoint of the shape of a coil winding, it is conceivable that each twocoil conductors of the armature coil 4 are formed. Therefore, thearmature coil 4 may be made such that concave and convex shapes areformed between a first layer and a second layer and between a thirdlayer and a fourth layer; and the concave and convex shapes are notformed between the second layer and the third layer, but may be formedin a substantially straight line.

Further, in the case of forming the shape between the coil conductors ofthe armature coil 4, it may be formed not only in the concave and convexshapes, but also it may be such that one coil conductor is formed in anS shape or a wave shape and another coil conductor is formed in aninverse S shape or an inverse wave shape along the S shape or the waveshape. The armature coil 4 extended from the slot 3 does not need to beforcedly formed as described above; however, a part of the armature coil4 extended from an end portion of the slot 3 is formed as describedabove, whereby it becomes: the start of crossover for the winding of thearmature coil 4, positioning of passing the coil into the slot 3, orprevention from interfering with an edge portion of the slot end.

Embodiment 2

Next, Embodiment 2 of the present invention will be described withreference to FIGS. 2(a), 2(b). In this case, a method of forming thearmature coil in the aforementioned Embodiment 1 will be described.FIGS. 2(a), 2 (b) are each a coil forming process view by a coil formingapparatus in the armature coil according to Embodiment 2 of the presentinvention.

FIGS. 2(a), 2(b) each shows the forming apparatus by an upper metal die10 and a lower metal die 11; and the lower metal die 11 has a groove 13whose width gets narrower in proportion to its depth. The shape of thegroove 13 is substantially the same as the shape of a slot 3 into whichrespective coil conductors of an armature coil 4 are inserted. Moreparticularly, a groove shape at a position shown by L1 in FIG. 2 (b)needs to be the same as the slot shape. Since other position is notdirectly involved in an improvement of a space factor, the whole of thegroove 13 does not need to be formed in a funnel shape and may beparallel straight lines each having a width of a degree capable ofarranging the coil conductors of the armature coil 4. Therefore, thereis shown a case where the groove 13 is formed in the funnel shape as faras the height of L2 in FIG. 2(b) and is formed in a straight line froman upper portion thereof. With this configuration, in the drawing, evenwhen a first coil conductor strand 4 a 1, a second coil conductor strand4 b 1, a third coil conductor strand 4 c 1, and a fourth coil conductorstrand 4 d 1 are sequentially arranged from an upper opening portion ofthe lower metal die 11, lamination with large off-center in the rightand the left in the drawing is reduced.

An upper end portion 12 a of a lower opening metal die 12 is preferableto be similar to the shape of a slot opening portion; however, asubstantially straight line is also permissible. The upper metal die 10has a pressing body 10 a having a shape similar to the width of thegroove 13; and an end portion of the pressing body 10 a has a rod-shapedend portion 10 b slightly narrower than the width of the groove 13.Furthermore, the shape of the rod-shaped end portion 10 b of the uppermetal die 10 is similar to the shape of a back portion of the slot 3. Inthe forming apparatus having such upper metal die 10 and lower metal die11, first, the first coil conductor strand 4 a 1, the second coilconductor strand 4 b 1, the third coil conductor strand 4 c 1, and thefourth coil conductor strand 4 d 1 are sequentially arranged in thegroove 13. FIGS. 2(a), 2 (b) each shows a case where four round wirecoil conductor strands are formed at the same time. However, the methodof forming the armature coil is not limited to this, but is irrespectiveof the cross-sectional shape of the coil conductor strand, and is notconcerned to the number of coil conductor strands if the number of thecoil conductor strands is a plural number.

A part of the outer periphery of the first coil conductor strand 4 a 1of a lowermost portion is stopped by coming in contact with inner wallsof the groove 13; and thereon, the second coil conductor strand 4 b 1,the third coil conductor strand 4 c 1, and the fourth coil conductorstrand 4 d 1 are arranged in sequence. This state is a state beforestarting forming and is the state shown by FIG. 2(a). Subsequently, thepressing body 10 a of the upper metal die 10 moves down in the groove 13from the upper opening portion of the lower metal die 11. Then, thepressing body 10 a of the upper metal die 10 further moves down to pressthe respective coil conductor strands by pressing force F1; and thus,deformation is gradually forwarded from the first coil conductor strand4 a 1 located at the lower most portion along the groove width. Nothingexists between the respective coil conductor strands; and therefore, thecoil conductor strands are formed more elongated toward the coilconductor strand having a large aspect ratio, that is, deformed in aconvex shape. Then, the subsequent coil conductor strand is formed in aconcave shape by the influence thereof and the other side is formed in aconvex shape; and this is repeated in the subsequent coil conductorstrands in sequence.

FIG. 2(b) shows a state where the upper metal die 10 is restricted bythe lower opening metal die 12 and the first coil conductor 4 a, thesecond coil conductor 4 b, the third coil conductor 4 c, and the fourthcoil conductor 4 d of the armature coil 4 are formed. After that, theupper metal die 10 is returned to an original position; the loweropening metal die 12 is moved in the upper direction in the drawing; thefirst coil conductor 4 a, the second coil conductor 4 b, the third coilconductor 4 c, and the fourth coil conductor 4 d of the armature coil 4are pushed up; and the respective coil conductors of the armature coil 4are removed from the lower metal die 11 to complete the forming process.And then, the first coil conductor 4 a, the second coil conductor 4 b,the third coil conductor 4 c, and the fourth coil conductor 4 d of theformed armature coil 4 are sequentially inserted into the slot 3 formedin the stator core 1 of the stator.

As described above, the first coil conductor strand 4 a 1, the secondcoil conductor strand 4 b 1, the third coil conductor strand 4 c 1, andthe fourth coil conductor strand 4 d 1 of the armature coil 4 arrangedin the tapered groove 13 are pressed to deform in sequence from the coilconductor strand of the armature coil 4 having a higher aspect ratioand, at the same time, are pressed so as to transfer the deformationbetween the coil conductor strands of the armature coil 4; and thus, onecoil conductor of the armature coil 4 is formed in the convex shape andanother next coil conductor of the armature coil 4 is formed in theconcave shape conforming to the convex shape. This enhances contactproperties between the coil conductors of the armature coil 4 and thespace factor can be improved when the first coil conductor 4 a, thesecond coil conductor 4 b, the third coil conductor 4 c, and the fourthcoil conductor 4 d of the armature coil 4 pass through the slot 3 formedin the stator core 1 of the stator.

The rod-shaped end portion 10 b of the upper metal die 10 continues topress the first coil conductor strand 4 a 1, the second coil conductorstrand 4 b 1, the third coil conductor strand 4 c 1, and the fourth coilconductor strand 4 d 1 of the armature coil 4; and therefore, it becomespossible to concentrate pressure, pressing force becomes smaller ascompared in the case of pressing the flat shaped upper and lower metaldies, and the scale of the metal dies can also be miniaturized.Incidentally, it is possible to improve for easiness of forming byusing, for example, the first coil conductor strand 4 a 1, the secondcoil conductor strand 4 b 1, the third coil conductor strand 4 c 1, andthe fourth coil conductor strand 4 d 1 of the armature coil 4, eachhaving a cross-section nearer to a trapezoid shape than a round wire,which facilitates to deform by once heating the first coil conductorstrand 4 a 1, the second coil conductor strand 4 b 1, the third coilconductor strand 4 c 1, and the fourth coil conductor strand 4 d 1 ofthe armature coil 4. Further, the first coil conductor 4 a, the secondcoil conductor 4 b, the third coil conductor 4 c, and the fourth coilconductor 4 d of the armature coil 4 may be of a type in which, like apine needle shaped segment coil, a winding is formed after inserting inthe slot or may be one in which a continuous wire is wound to form acoil winding shape.

Embodiment 3

Next, Embodiment 3 of the present invention will be described withreference to FIGS. 3(a), 3(b). FIGS. 3(a), 3(b) are each a coil formingprocess view by a coil forming apparatus in an armature coil accordingto Embodiment 3 of the present invention.

The coil forming apparatus in Embodiment 3 of the present invention iscomposed of four metal die portions. For example, the coil formingapparatus includes: a lower metal die 14; an end metal die 15 which ismounted on the lower metal die 14 and has a shape similar to a slot endportion; a back portion metal die 16 which is mounted on the lower metaldie 14 and is similar to a slot back portion; and an upper metal die 17.Incidentally, the upper metal die 17 has an inclined surface portion 17a inclined toward the right direction in the drawing and is made suchthat the inclined surface portion 17 a of the upper metal die 17 can bepressed until coming in contact with the upper surfaces of the end metaldie 15 and the back portion metal die 16 by pressing force F2. The endmetal die 15 and the back portion metal die 16 may be integrated withthe lower metal die 14.

The coil forming apparatus is composed of the above-described respectivemetal dies; and as shown in FIG. 3(a), a state where the upper metal die17 is set in the upper direction is an initial state. In this state, afirst coil conductor strand 5 a 1, a second coil conductor strand 5 b 1,a third coil conductor strand 5 c 1, and a fourth coil conductor strand5 d 1 of an armature coil 5 are set between the end metal die 15 and theback portion metal die 16. In this Embodiment 3, a quadrilateralcross-section coil conductor is used; however, a round wire orelliptical cross-section coil conductor may be permissible. The settingof the first coil conductor strand 5 a 1, the second coil conductorstrand 5 b 1, the third coil conductor strand 5 c 1, and the fourth coilconductor strand 5 d 1 of the armature coil 5 is preferable to be setwith a slight gap, if possible. In this regard, however, as therespective coil conductor strands are deformed on the way to forming,other coil conductor strand is pushed in the left direction in thedrawing; and therefore, the gap therebetween may be reasonable.

After the first coil conductor strand 5 a 1, the second coil conductorstrand 5 b 1, the third coil conductor strand 5 c 1, and the fourth coilconductor strand 5 d 1 of the armature coil 5 are set, the upper metaldie 17 is moved down to start pressing. This pressing is pressed by theinclined surface portion 17 a of the upper metal die 17 from the firstcoil conductor strand 5 a 1 at the right end in the drawing to thesecond coil conductor strand 5 b 1, the third coil conductor strand 5 c1, and the fourth coil conductor strand 5 d 1 in sequence. Lastly, thepressing is carried out as far as the fourth coil conductor strand 5 d 1at the left end; and the pressing is completed at the time when theinclined surface portion 17 a of the upper metal die 17 comes in contactwith the upper surfaces of the end metal die 15 and the back portionmetal die 16. More specifically, the shape of the each metal die isdetermined so that a space formed by the upper metal die 17 and thelower metal die 14 is substantially the same as a slot space. Therefore,as a result, the pressed respective coil conductor strands are formedalong the slot shape.

Furthermore, a forming order is such that the pressing is made to deformfrom the right side coil conductor strand and thus the left side surfaceof the right end coil conductor strand is formed in a most convex shape;the right side surface of the next coil conductor strand is formed in aconcave shape in reaction to the convex shape; and the left side surfacethereof is formed in a convex shape and such a deformation is forwardedin sequence. As described above, when the pressing is carried out byplanes from both sides of the coil conductor strand, to be exact, thestate of the convex shape is formed in a wave shape composed of a partlyconvex shape and a partly concave shape. This concave and convex waveshape turns into a reverse concave and convex wave shape on the nextcoil. Furthermore, an aspect ratio gets larger toward the right sidecoil conductor strand and therefore its concave and convex state alsogets larger toward the right side coil conductor strand.

As described above, as shown in FIG. 3(b), a first coil conductor 5 a, asecond coil conductor 5 b, a third coil conductor 5 c, and a fourth coilconductor 5 d of the armature coil 5 are formed by pressing and formingfrom the upper and lower surfaces of the coil conductor strands by theupper metal die 17 and the lower metal die 14; and the concave andconvex state is formed between the coil conductors. Then, when the firstcoil conductor 5 a, the second coil conductor 5 b, the third coilconductor 5 c, and the fourth coil conductor 5 d of the armature coil 5are inserted into a slot 3 formed in a stator core 1, the degree ofjoining between the coil conductors is increased; and as a result, aspace factor is improved. Incidentally, overheat process of the firstcoil conductor strand 5 a 1, the second coil conductor strand 5 b 1, thethird coil conductor strand 5 c 1, and the fourth coil conductor strand5 d 1 of the armature coil 5 may be previously performed so as to beeasily formed.

Incidentally, the present invention can freely combine the respectiveembodiments and appropriately change and/or omit the respectiveembodiments, within the scope of the present invention.

DESCRIPTION OF REFERENCE NUMERALS

1 Stator core, 2 Tooth, 3 Slot, 4 Armature coil, 4 a First coilconductor, 4 b Second coil conductor, 4 c Third coil conductor, 4 dFourth coil conductor, 5 Armature coil, 5 a First coil conductor, 5 bSecond coil conductor, 5 c Third coil conductor, 5 d Fourth coilconductor, 10 Upper metal die, 11 Lower metal die, 12 Lower openingmetal die, 13 Groove, 14 Lower metal die, 15 End metal die, 16 Backportion metal die, Upper metal die.

The invention claimed is:
 1. A method of manufacturing an armature coil,comprising the steps of: having a lower metal die, which is providedwith an end metal die at a first side end portion of the lower metal dieand a back portion metal die at a second side end portion of the lowermetal die opposite of the first side end portion, and an upper metal diewhich is provided with an inclined portion on a lower metal die side ofthe upper metal die, the upper metal die configured to be pressed, suchthat a space formed by the lower metal die, the end metal die, the backportion metal die, and the upper metal die is substantially the same asa shape of a slot of a stator core, and a width of the space, in a firstdirection from the upper metal die to the lower metal die, getsgradually narrower in a second direction, that is towards the end metaldie from the back portion metal die and perpendicular to the firstdirection, when the upper metal die is moved to come in contact with anupper surface of the end metal die and an upper surface of the backportion metal die; arranging a plurality of coil conductors of thearmature coil between the end metal die and the back portion metal dieon the lower metal die, the plurality of coil conductors arranged withrespect to each other in the second direction; pressing, with the uppermetal die in the first direction, the plurality of coil conductorsarranged between the end metal die and the back portion metal die on thelower metal die such that: the upper metal die reaches a position inwhich the upper metal die comes into contact with the upper surface ofthe end metal die and the upper surface of the back portion metal die,and in the position, (i) an amount of flattening of the plurality ofcoil conductors in the first direction increases towards the end metaldie such that a first coil conductor that is closest to the end metaldie, from among the plurality of coil conductors, is flattened the mostfrom among the plurality of coil conductors, (ii) aspect ratios ofcross-sections of the plurality of coil conductors decreases towards theback portion metal die such that a cross-section of the first coilconductor has a highest aspect ratio from among the plurality of coilconductors, and (iii) in a cross-sectional view of the plurality of coilconductors, one coil conductor from among the plurality of coilconductors is formed to include a first convex shape and another coilconductor from among the plurality of coil conductors is formed toinclude a first concave shape, that is along and directly facing thefirst convex shape of the one coil conductor; and removing the pluralityof coil conductors from the lower metal die after forming the firstconvex shape and the first concave shape.
 2. The method of manufacturingthe armature coil according to claim 1, wherein the arranging comprisesarranging the plurality of coil conductors such that the plurality ofcoil conductors are separated from each other in the second direction byat least one gap.
 3. The method of manufacturing the armature coilaccording to claim 1, wherein the pressing comprises pressing such that,in the position, in the cross-sectional view of the plurality of coilconductors, the one coil conductor is formed in a wave shape to includethe first convex shape as a first partly convex shape and a secondpartly concave shape, and the another coil conductor is formed toinclude the first concave shape as a first partly concave shape and asecond partly convex shape, and the second partly concave shape is alongand directly facing the second partly convex shape while the firstpartly convex shape is along and directly facing the first partlyconcave shape.
 4. The method of manufacturing the armature coilaccording to claim 1, wherein the one coil conductor is the first coilconductor.